[Suggestion] podman kill on closing distrobox ephemeral

**Is your feature request related to a problem? Please describe.**
Yeah. On my system (Void musl), `podman stop` does not stop a rootless container, erroring with `Error: given PID did not die within timeout`. Thus the container does not actually get deleted, defeating the point of having an 'ephemeral' container.

**Describe the solution you'd like**
In the case of podman, close ephemeral containers with `podman kill`. This may also require a related `distrobox kill` to be called by distrobox-ephemeral.

**Describe alternatives you've considered**
Fixing the original problem of containers not being stopped properly (I have no idea how to do this)
Running podman --rm

**Additional context**
On void, at least for me, I sometimes have to use `sudo pkill` instead of `pkill`. I'm not sure why. This is probably related.
podman kill always works on my system, rootless or otherwise.